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STAGE 1: Main Sequence A star's life begins when nuclear reactions start deep in the core. Hydrogen nuclei are fused to form a helium nucleus. Each helium nucleus has slightly less mass than the hydrogen...more

STAGE 2: Red Giant Phase When the star uses up its hydrogen fuel in the core, it can no longer hold up its outer layers. They fall inward. The center gets hotter. The hot temperatures cause the outer...more

STAGE 3: The Outer Layers Blow Off As the star expands,the outer layers blow off at an incredible rate. A star can lose more than half of its mass during this stage. The gas cloud surrounding the star...more

STAGE 4: White Dwarf When the fuel is used up, there is nothing to hold the star's layers up against gravity and the star begins to collapse. Gravity squeezes the star down into a very small size. As...more

STAGE 5: Black Dwarf White dwarfs are some of the hottest objects in the known universe with temperatures ranging from 30,000 K to 200,000 K. They continue to radiate their immense internal energy into...more

Even though the sleeping man is no longer on the bed, you can still see where he was lying down. The heat from his body warmed up the bed sheets which are now radiating infrared light toward your eyes....more

All warm objects (not just people) radiate in the infrared. Warmer objects give off more infrared radiation. Very hot objects radiate other types of light in addition to infrared. Click on the picture...more